I hope we never get a sports scientist serial killer. Preying on unsuspecting gym-goers, assessing body composition in his mothers basement. I will have a nightmare tonight.
What I don't understand: How can we even begin to measure the error of those methods, if we have no way of measuring actual bodyfat? Where are we getting the "real value" from, that we compare the results with?
cadavers would probably be the best way to do it, since you could perform the tests and then dissect them. but there's some very obvious problems with that.
Oh yeah, I should have addressed that in the video. It's covered in the article. The criterion measure is usually a full 4-C body comp assessment, which is actually very good, but is also (almost entirely) inaccessible for most people.
I get what you guys are saying about the inter-person 'un'reliability for body composition methods, like dexa, as in, each person tested in the large study had a reasonably significant variation in margin of error, but (and I'm happy to be corrected) you guys are extrapolating that into intra-person reliability, and I'm not sure we can do that. I haven't had the time to read all the studies and their methods you've talked about, but were they repeated measures/dependent studies, as in, were the same participants tested under the same conditions at different time points, and in particular, with close or distant proximity and compared to the gold standard? From a scientific perspective, if they were to test the same subjects, in the same machine repeatedly 3 times in quick succession, and compared those results to the study gold standard, '4-C body comp' , we would get a good idea of the intra-person reliability. If we then took that same person and tested them again in 6 months, post training, but the same prep conditions, say fasted for 12 hours, reasonably similar diet the 2 days leading up, litres of water, grams of salt, not saunaing (sorry if thats not a word haha), scan at 8am or what ever, scanned them 3 times and compared to 4-C body comp, then we would not only then have a good idea of intra-person reliability at one time point, but would start at least to get an idea of consistency within individuals, because I wonder if the major variation, as quoted by you guys, comes with individual variation and prep conditions, rather than just marked variation from the machine itself. I would be surprised if you scanned 1 person repeatedly in quick succession (with DEXA) you would get such significant variation (maybe you would, but this type of study wasn't referred to at all). I mentioned scientifically earlier, purely so I could say now, anecdotally, even with BIA myself, I have gone through prolonged periods of daily weighing and BIAing myself on the same diet, same time everyday, morning, post morning pee and crap, and I have had marked consistency in BF%. The variation came when I'd had chinese or pizza the day before, and then the BF% moves back towards the average value over 2-3 days on normal diet. Back to my above comments, so if there was actually intra-person consistency, in the individual who keeps themself consistent, then it would still be a useful measure of progress (esp. For the physique competitor), if not purely for the fact that you remove significant personal bias and result normalisation, from seeing yourself daily. I wouldn't be the first person to look at my gains and not see them, or look at my far too quick bulk and be in denial, so yes, putting a number to that is just honest, of course if its consistent and reliable enough. And no, another person who lives with you is not more reliable or less biased necessarily, because my wife forever just says, "I dunno, you look good to me" (bless her soul, but damn it I need something more than unconditional love 😂😂 - jokes aside). Interested in your thoughts on this, or if you've seen this type of repeated measures study performed to assess intra-person reliability, and what the results were? I guess if you have and the results were, scan 1 at 1 min, scan 2 at 5 mins, and scan 3 at 10 mins, 15%, 11%, 18%, then I guess I just wasted a whole bunch of time writing this, but at least I got it off my chest 😂😂 but if not, perhaps that should be a future direction.
Bathroom Scales seem to have all these same problems, but that doesn't stop them from being useful. MacroFactor uses its Weight Trend algorithm to make bathroom scale weight measures reliable enough to base the whole app around them. Why can't the same be done for any or all of these at home methods of body comp assessment? Be it running average, average of several methods, or a full-on algorithm like Weight Trend? And wouldn't such a BodyComp Trend be a fantastic feature to have on MacroFactor, if so!
Im curious what would happen if you just do 2 dexa scans in a very short period of time. (Maybe 5mins or 1 day). 🤔 - A man who believed in dexa and is now heartbroken 😔
I see a lot of people who think they have to "get down to 12% and then bulk" which is probably one drivers of trying to measuring body comp. It comes from the idea that a dieted down person at 12% has a better p-ratio than they did before they dieted - which IIRC from your previous discussions is not exactly true.
seems like the best you can do is have a bodyweight goal and just get stronger/improve performance in your sport. If you improve your compound lifts and maintain the same weight, seems safe to say you've converted some body mass. how much? use calipers if you really care.
I would be interested how this works in regards to the discussion of BMI. The anecdotal argument against using it as a significant health marker is often that it does not take composition into play. If the composition isn't important then does that mean BMI is actually a better health metric than we give it credit for?
I hope we never get a sports scientist serial killer. Preying on unsuspecting gym-goers, assessing body composition in his mothers basement. I will have a nightmare tonight.
What I don't understand: How can we even begin to measure the error of those methods, if we have no way of measuring actual bodyfat? Where are we getting the "real value" from, that we compare the results with?
Well you could use a calibrated manikin, error propagation calculations, maybe some fancy standard addition linear regression
cadavers would probably be the best way to do it, since you could perform the tests and then dissect them. but there's some very obvious problems with that.
Right? I've always had this question. I guess you can scan a dead person and then weigh all their fat and muscle but idk if anyone's doing that...
Oh yeah, I should have addressed that in the video. It's covered in the article. The criterion measure is usually a full 4-C body comp assessment, which is actually very good, but is also (almost entirely) inaccessible for most people.
I get what you guys are saying about the inter-person 'un'reliability for body composition methods, like dexa, as in, each person tested in the large study had a reasonably significant variation in margin of error, but (and I'm happy to be corrected) you guys are extrapolating that into intra-person reliability, and I'm not sure we can do that. I haven't had the time to read all the studies and their methods you've talked about, but were they repeated measures/dependent studies, as in, were the same participants tested under the same conditions at different time points, and in particular, with close or distant proximity and compared to the gold standard? From a scientific perspective, if they were to test the same subjects, in the same machine repeatedly 3 times in quick succession, and compared those results to the study gold standard, '4-C body comp' , we would get a good idea of the intra-person reliability. If we then took that same person and tested them again in 6 months, post training, but the same prep conditions, say fasted for 12 hours, reasonably similar diet the 2 days leading up, litres of water, grams of salt, not saunaing (sorry if thats not a word haha), scan at 8am or what ever, scanned them 3 times and compared to 4-C body comp, then we would not only then have a good idea of intra-person reliability at one time point, but would start at least to get an idea of consistency within individuals, because I wonder if the major variation, as quoted by you guys, comes with individual variation and prep conditions, rather than just marked variation from the machine itself. I would be surprised if you scanned 1 person repeatedly in quick succession (with DEXA) you would get such significant variation (maybe you would, but this type of study wasn't referred to at all). I mentioned scientifically earlier, purely so I could say now, anecdotally, even with BIA myself, I have gone through prolonged periods of daily weighing and BIAing myself on the same diet, same time everyday, morning, post morning pee and crap, and I have had marked consistency in BF%. The variation came when I'd had chinese or pizza the day before, and then the BF% moves back towards the average value over 2-3 days on normal diet.
Back to my above comments, so if there was actually intra-person consistency, in the individual who keeps themself consistent, then it would still be a useful measure of progress (esp. For the physique competitor), if not purely for the fact that you remove significant personal bias and result normalisation, from seeing yourself daily. I wouldn't be the first person to look at my gains and not see them, or look at my far too quick bulk and be in denial, so yes, putting a number to that is just honest, of course if its consistent and reliable enough. And no, another person who lives with you is not more reliable or less biased necessarily, because my wife forever just says, "I dunno, you look good to me" (bless her soul, but damn it I need something more than unconditional love 😂😂 - jokes aside).
Interested in your thoughts on this, or if you've seen this type of repeated measures study performed to assess intra-person reliability, and what the results were? I guess if you have and the results were, scan 1 at 1 min, scan 2 at 5 mins, and scan 3 at 10 mins, 15%, 11%, 18%, then I guess I just wasted a whole bunch of time writing this, but at least I got it off my chest 😂😂 but if not, perhaps that should be a future direction.
Great content gentlemen, keep it up!
Bathroom Scales seem to have all these same problems, but that doesn't stop them from being useful. MacroFactor uses its Weight Trend algorithm to make bathroom scale weight measures reliable enough to base the whole app around them. Why can't the same be done for any or all of these at home methods of body comp assessment? Be it running average, average of several methods, or a full-on algorithm like Weight Trend? And wouldn't such a BodyComp Trend be a fantastic feature to have on MacroFactor, if so!
Im curious what would happen if you just do 2 dexa scans in a very short period of time. (Maybe 5mins or 1 day). 🤔
- A man who believed in dexa and is now heartbroken 😔
probably not well advised, since it's a full body x-ray
Anyone have the timestamp for the issues with Dexa? I use dexa onluy fasted in the morning every 6 mos
10:28
Oh sorry, the problems with it are listed at 15:20
@@jakechambers3059 thanks bro
I see a lot of people who think they have to "get down to 12% and then bulk" which is probably one drivers of trying to measuring body comp. It comes from the idea that a dieted down person at 12% has a better p-ratio than they did before they dieted - which IIRC from your previous discussions is not exactly true.
seems like the best you can do is have a bodyweight goal and just get stronger/improve performance in your sport. If you improve your compound lifts and maintain the same weight, seems safe to say you've converted some body mass. how much? use calipers if you really care.
I want to know my body fat percentage for a sense of personal achievement more than anything, truthfully.
The exhaling air for the dunk tank and waiting for an accurate measurement is miserable.
100%. It sucks ass.
For the algorithm
I would be interested how this works in regards to the discussion of BMI. The anecdotal argument against using it as a significant health marker is often that it does not take composition into play. If the composition isn't important then does that mean BMI is actually a better health metric than we give it credit for?
Waist circumference and height/waist ratios seem to be better health markers than BMI. Probably more useful than either BMI or bf%
@@strongerbyscience Thank you. I had started using that with clients after reading Maffetone. Appreciate the additional endorsement of the approach.
Where did you get that body composition isn't important? Did I miss that part of the video?